Re: VALVE TAP
I use 10W-40 synthetic. I'm thinking 5w-30 would probably be ok, but consult your owners manual. The guys are right about 20w-50... too viscous. The oil passages are tiny in some places of the engine, so there needs to be an oil "light" enough to flow a decent volume through them.
I think the reason we all hear so much valve component noise is the cam "directly" lifts the valve ( yeah there's two solid metal pieces between the cam and the actuall valve). When the engine is cold those metal parts have more of a gap inbetween them.. when things heat up the gap lessens and the engine quiets down some.
I've found it difficult to diagnose all engine noises on my CBR... although i believe most of them are just normal.